The diagnosis, treatment and prevention of aluminum-related bone disease has substantially improved for the management of patients with end-stage renal disease. In contrast, secondary hyperparathyroidism remains a major clinical problem in the treatment with vitamin D sterols. It is currently unknown, however, whether parenteral calcitriol can adequately control secondary hyperparathyroidism in adult dialysis patients, and the response of pediatric dialysis patients to such intervention remains to be evaluated. Moreover, direct comparison of the secondary hyperparathyroidism have not been done in order to asses if one mode of treatment is more advantageous for the control of secondary hyperparathyroidism. Unlike the situation with hemodialysis, repeated intravenous injections of calcitriol cannot be given to patients receiving CAPD/CCPD, and intraperitoneal calcitriol administration using regular dialysate exchange bags does not enhance sterol bioavailability compared to oral doses of the hormone. Since CAPD/CCPD are increasingly used, particularly in children, such studies seem warranted for children with end-stage renal disease. To test this hypothesis, therefore, we propose to perform prospective randomized studies in pediatric dialysis patients, to compare the effects of the different routes of calcitriol administration on the control of the skeletal features secondary hyperparathyroidism. A comparative clinical trial of oral versus intraperitoneal calcitriol will be performed in pediatric patients with secondary hyperparathyroidism and treated with peritoneal dialysis. Therapeutic responses will be judged by changes in biochemical indices of parathyroid hormone secretion and by changes in quantitative histomorphometric variables in bone biopsies obtained before and after treatment. The information gained from these studies will considerably enhance our knowledge in the treatment of secondary hyperparathyroidism in uremic children.